1. Field of the Invention
This invention relates to a fluorescent lamp and, more specifically, to a fluorescent lamp used as a back light source for liquid crystal displays used as a display for portable computers or a reading light source for facsimiles.
2. Background Art
An example of this type of fluorescent lamp of the prior art is, as shown by laid-open Japanese Patent Application No. Hei 3-225745, a rare gas discharge lamp (fluorescent lamp) in which a fluorescent layer is formed on the inner surface of a tubular glass bulb, the tubular glass bulb is charged with a rare gas and a pair of belt-shaped electrodes are formed on almost the total length of the outer surface of the glass bulb.
However, in the fluorescent lamp of the prior art described above, lighting voltage is high. Since lighting voltage increases as the pressure of the rare gas charged into the glass bulb rises, the pressure of the charged gas is limited to 100 torr or less to make it practical lighting voltage as disclosed in the above publication. As a result, illuminance sufficiently high to meet an application purpose cannot be obtained.